How many planets have moons?

A:

Quick Answer

Six of the eight planets in the solar system are known to have moons. Mercury and Venus lack orbiting bodies of any significant size. Earth has one moon, Mars has two, and the gas giants have several moons each.

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According to the Planetary Society, the solar system has 18 or 19 moons that are large enough for gravity to give a spherical shape. Uncertainty surrounds Neptune's moon Proteus, which is just at the minimum threshold for mass.

According to NASA, in 2014, 146 moons were confirmed to orbit planets in the solar system. Another 27 moons awaited confirmation. Six moons were known to exist around dwarf planets such as Pluto and the asteroid Ida.